One of our favorite professional websites that

can help build your specialty practice is

The educational resource for customized contact lenses offers a wealth of information for you, your staff & your patients! You will find helpful webinars, fitting tools, 

a FREE practitioner locator 

& so much more!

For a great overview of what to expect with corneal reshaping and answers to common questions, be sure your corneal reshaping candidates & their parents know about the Paragon CRT consumer site:

www.crtvision.com

Definitive SiHy Material is Truly Unique

by Mike Johnson, FCLSA

Director of Consultation Services 

I have been wearing Art Optical's Intelliwave Multifocal design in the Definitive SiHy material for approximately 2 years. I can honestly say that the comfort is extraordinary and the vision I obtain is excellent at both distance and near. I am a moderate myope in the -5.00 range OU with about -0.75 with-the-rule cylinder OD and sphere on the OS with a +2.50 add OU. I have tried sphere power only for my OD but in the long run found that correcting my cylinder on the right eye does provide added distance clarity. There are several studies in process to determine if incorporating low cylinder values into a soft lens Rx is noticeable and ultimately beneficial for patients. From my perspective, there is no doubt that including cylinder has enhanced my overall acuity.  

I have also worn Bausch + Lomb PureVision Multifocals in the past. I had always obtained good comfort with PureVision. I know that some patients have had comfort issues with hyper DK SiHy materials, but I am one of the lucky ones who adapts well to just about any contact lens material and/or design. I functioned very well binocularly with the high add version in both eyes but found I needed to over minus the distance power in my OD (dominant) and ended up slightly under corrected in the OS, which aided my near vision.

I have noticed some differences with the Definitive material compared to PureVision that your patients will also notice if you switch them from a hyper DK SiHy to Intelliwave in the Definitive SiHy material. First and foremost, the Definitive material does not physically feel or handle like other SiHy materials. When I was first wearing PureVision, I noted that the material felt very rubbery in my hands and had some elasticity to it. I would not say that they were indestructible, but they had an added stability that I was not used to seeing in hydrogel materials. The first thing I noticed about the Definitive material is that it handled much like a normal hydrogel material. It is soft and slippery feeling, very flexible and does not have that rubbery stiffness that I associated with PureVision. This is because the modulus (stiffness factor) of Definitive is .39 compared to SiHy materials that range from >.60 up to nearly 1.4 (MPa).

As the only latheable silicone hydrogel material approved in the U.S., Definitive gives us the ability to manufacture virtually any Rx your patient requires. Partnered with our award-winning Intelliwave design platform, from an acuity and performance standpoint, our results and satisfaction rates are exceptional.

Definitive is also unique in that it is the only SiHy material available in the U.S. that does not require plasma treatment. It has a 74% water content and you would think that this would lead to dryness issues as wearing time is pushed toward the end of the day; however, I was pleasantly surprised to find that this was not the case with my personal lens wearing experience. Definitive tends to stay very wet throughout the day for me, even when I am pushing 16 plus hours of wearing time. 

I have learned from my own experiences with handling the Definitive soft lens material that patients who are prescribed Intelliwave lenses in Definitive should receive additional instructions about the handling differences. If a patient tries to handle a Definitive lens the same way they have handled hyper DK SiHy materials, they are likely to experience some concerns. Because of this, Art Optical is now sending a helpful patient handling reminder that will be included with each Definitive lens order shipped. This reminder, titled "Important Information about your New Contact Lenses" will provide timely information and recommendations that will ensure your patients have a good experience with their Intelliwave lenses in the Definitive material. There is also a practitioner piece titled "Important Information about your Contact Lens Order" included, and is intended to help practitioners understand the need to inform the patient about the benefits and handling differences of Definitive material.  

Nearly every optometric practice has multiple Post-LASIK patients with near vision complaints. When LASIK was performed on them many years ago, they had no clue that they would once again be forced to wear correction at the onset of presbyopia. A number of these patients are also experiencing some distance vision regression, and still others are dealing with minor corneal irregularities that have decreased the effectiveness of their overall acuity.

Art Optical is one of the first custom contact lens manufacturers in the country to offer a GP lens design that satisfactorily addresses these issues. CLASIKcn is NOT a revamped version of an existing center distance multifocal design used for normal corneas. It was specifically developed for Post-LASIK, as well as Post-RK patients who have reached mature presbyopic stages.

Simply put, CLASIKcn is a reverse geometry posterior surface lens combined with an anterior center near multifocal target. The posterior surface conforms to the surgically altered shape of the cornea. The back surface can be designed from corneal topography, with the use of a loaner fitting set or with pre- and post-surgical K's and spectacle Rx. The base curve is designed to align with the flatter central cornea and the periphery is made steeper than the central base curve to match the unaltered peripheral cornea. This reverse geometry design concept provides a good alignment fit centrally and peripherally. It provides excellent centration and allows the patient to adapt very quickly.

The center near multifocal target provides simultaneous acuity, much like the center near option in many soft multifocal lens designs. A standard target of 2 mm is used for the center near optic which includes a full spherical near power add that slowly shifts power from full near to full distance acuity. This zone diameter can be adjusted larger or smaller to adapt to any pupil diameter. Using a center near optic means that the distance power is not affected by pupil dilation. The posterior optical zone extends well beyond the ablation/treatment zone peripherally which assures that there is no interruption of distance vision.

Are you prepared for the onslaught? The number of Post-LASIK patients reaching presbyopic stages will increase dramatically over the next 5 to 10 years. The patients you are seeing now are only the tip of the iceberg, so to speak. CLASIKcn will be there for you every step of the way. Contact our Consultation Department to learn more about this exciting new design concept and re-introduce your next Post-LASIK presbyopic patient to life without readers...again!

A Closer Look at Corneal Toricity

When a patient presents with keratometer readings and refraction resulting in 3.00 diopters or greater in cylinder, the use of a toric back surface design should be considered to provide the most optimal fit and acuity. Although topography is not critical for designing toric lenses, as toric back surface lenses are quite often successful when designed empirically, topography can offer very helpful information regarding the length and position of the toricity. The topography in Fig 1 shows limbus to limbus corneal cylinder while Fig 2 shows a more apical toricity. Knowing this detail will help in the selection of the diameter and optic zone to further facilitate a successful outcome.

Figure 1

Figure 2

Limbus to limbus cylinder, as noted in Fig 1, is more likely to require a toric back surface to achieve the best alignment and stability. Because the toricity covers a more significant portion of the cornea, a larger overall diameter and more importantly, a larger optic zone, will provide an optimal fitting relationship by extending the base curve toricity further into the periphery of the lens. It may also be beneficial to incorporate toric peripheral curves which will assist with the stability of the fit. Art Optical's toric generating lathes automatically incorporate toric peripheries that are equal to the base curve toricity.  

Apical cylinder, as seen in Fig 2, allows us to consider more fitting options such as the use of an aspheric back surface design, like Boston Envision, to provide an adequate fit and acceptable acuity level. However, even with this type of cylinder an aspheric back surface is only beneficial up to approximately 3.00 diopters of corneal cylinder. After that point, a toric back surface will work better. Note that with apical cylinder the toricity covers only a small portion of the central cornea and the peripheral cornea takes on a more spherical appearance. A smaller optic zone would be recommended here to avoid peripheral seal off. This will put the base curve toricity just over the toric portion of the cornea and prevent the lens from rocking while still allowing adequate peripheral clearance outside of the OZ.

When we are thinking about using a toric back surface lens design, it is important to be certain that the corneal toricity being considered is regular cylinder. Regular cylinder will have a symmetrical, bow-tie pattern of toricity as depicted in Fig1 and Fig2. This will allow the toric base curves to align appropriately with the corneal cylinder axis since the flat and steep meridians are manufactured 90 degrees apart. An irregular toricity, as seen in Fig3, can have k-readings and refraction with significant cylinder that may even show the cylinder axes in alignment but because it does not have a symmetrical, bow-tie pattern, it is unlikely to be successful with a toric base curve. The back surface will not be able to seat into place causing rotation issues which will create fluctuations in the vision and result in unusual and unreliable over-refractions.

Figure 3

The purpose of this article is to recognize the benefits in determining the type of toricity we are dealing with and how this can assist the parameter selection for an optimal fit. For more specifics on base curve selection, see Mike Johnson's article: Bi-toric, Back Toric or Aspheric? in Consultant's Corner at www.artoptical.com